Tutu (My favorite character!)
Fang is a wolf that loves chairs!
Audie is another wolf that has a dream to be a model!
\[\begin{aligned} f(x) &= x^2 + 2x + 1 \\ &= (x + 1)^2 \\ &= x^2 + 2x + 1 \end{aligned}\]
Not every ML methods are fit to estimate \(O_i\) (e.g kNN)
The data (area A and B) is imbalanced (He and Garcia 2009).
There is a big overlap between units for model construction and units for estimation.
Non-probability sampling has the feature of high efficiency and low cost.
The inclusion mechanism of non-probability sampling is generally unknwon and could be selective (Spiegelhalter 2014).
Min. 1st Qu. Median Mean 3rd Qu. Max.
-2.30917 -0.49385 0.06176 0.09041 0.69182 2.18733